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ArduinoJson is a C++ JSON library for Arduino and IoT (Internet Of Things).

Features

• JSON decoding (comments are supported)
• JSON encoding (with optional indentation)
• MessagePack
• Elegant API, easy to use
• Fixed memory allocation (zero malloc)
• No data duplication (zero copy)
• Portable (written in C++98, can be used in any C++ project)
• Self-contained (no external dependency)
• Small footprint
• Input and output streams
• 100% code coverage
• Header-only library
• MIT License
• Comprehensive documentation

Compatibility

ArduinoJson works on the following hardware:

• Arduino boards: Uno, Due, Mini, Micro, Yun...
• Espressif chips: ESP8266, ESP32
• WeMos boards: D1, D1 mini, ...
• RedBearLab boards: BLE Nano, BLE Mini, WiFi Micro, LOLIN32...
• Teensy boards
• Intel boards: Edison, Galileo...
• Particle boards: Photon, Electron...
• Texas Instruments boards: MSP430...

ArduinoJson compiles with zero warning on the following compilers, IDEs, and platforms:

• Arduino IDE
• PlatformIO
• Energia
• Visual Micro
• Atmel Studio
• IAR Embedded Workbench
• Atollic TrueSTUDIO
• Keil uVision
• MPLAB X IDE
• GCC
• Clang
• Visual Studio

Quickstart

Deserialization

Here is a program that parses a JSON document with ArduinoJson.

char json[] = "{\"sensor\":\"gps\",\"time\":1351824120,\"data\":[48.756080,2.302038]}";

DynamicJsonDocument doc(1024);
deserializeJson(doc, json);

const char* sensor = doc["sensor"];
long time          = doc["time"];
double latitude    = doc["data"][0];
double longitude   = doc["data"][1];

See the tutorial on arduinojson.org

Serialization

Here is a program that generates a JSON document with ArduinoJson:

DynamicJsonDocument doc(1024);

doc["sensor"] = "gps";
doc["time"]   = 1351824120;

JsonArray data = doc.createNestedArray("data");
data.add(48.756080);
data.add(2.302038);

serializeJson(doc, Serial);
// This prints:
// {"sensor":"gps","time":1351824120,"data":[48.756080,2.302038]}

See the tutorial on arduinojson.org

Documentation

The documentation is available on arduinojson.org, here are some shortcuts:

• The Examples show how to use the library in various situations.
• The API Reference contains the description of each class and function.
• The FAQ has the answer to virtually every question.
• The ArduinoJson Assistant writes programs for you!

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